JPH03116162A - Wet image forming device - Google Patents

Abstract

PURPOSE:To reduce unpleasant odor and to effectively decompose ozone by making part f carrier liquid solvent of developer of silicone oil, and providing a mixing/discharging means whereby ozone and solvent mist effectively come into contact with each other. CONSTITUTION:The silicone oil is contained at least part of the carrier liquid solvent for the developer. Ozone generated by a main charger 14, a transfer charger 11, etc., is decomposed by bringing solvent mist, which is generated by developer on developing rollers 6 and 8, developer sticking to a photosensitive drum 1 and a transfer paper 21, a cleaning unit, a fixing unit, etc., into contact with the ozone; after that, the ozone/solvent mist collecting/mixing/discharging means (a duct 41 provided with a suction fan 40) is used to discharge them. Thus, the ozone is effectively decomposed, and the occurrence of unpleasant odor can be reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus such as a wet electrophotographic copying machine that forms an image on an electrophotographic photoreceptor or an electrostatic recording medium by a wet method, and in particular, to This invention relates to a method for decomposing ozone generated by solvent mist.

[Prior art]

In a wet type image forming apparatus such as a wet type electrophotographic copying machine, for example, an electrostatic latent image is formed on an electrophotographic photoreceptor (usually drum-shaped) by charging and image exposure, and this is developed with a developer to produce an image. The image is obtained by electrostatically transferring the image onto a transfer paper, and then thermally fixing the transferred image using a fixing roller. In this type of apparatus, corona discharge is applied to the photoreceptor, recording medium, or transfer paper during the latent image formation process or transfer process, so that ozone is generated within the apparatus. Particularly in recent years, static eliminators and the like installed for increasing the speed of copying machines, making wide-width copies, and stabilizing images are accompanied by discharge, and thus become a source of ozone generation. Although an increase in ozone concentration is undesirable from an environmental health perspective, the amount of ozone emitted from wet-type electrophotographic copying machines is smaller than that from dry-type copying machines.

It hasn't been much of a problem. This is because the solvent used as a carrier liquid for the developer evaporates from the developing area, or after development, it adheres to the photoreceptor drum or transfer paper and evaporates to form a mist, which decomposes when it comes into contact with ozone. It is from.

Note that in the past, the contact (mixing) between the ozone and solvent mist generated in the equipment was not done using special means, but was done in the hope that they would come into contact naturally, which was quite inefficient. However, the concentration of emitted ozone has not yet become a problem in wet image forming apparatuses.

On the other hand, the carrier liquid for the developer is generally nonane, decane,
Aliphatic hydrocarbon solvents such as isododecane and iooctane (
(usually used as a mixture), but although it has excellent properties as a carrier liquid, it is odorless and oxidized by high temperature heating during fixing, giving off a strange odor, making it unpleasant for the user. may give.

[Problems to be Solved by the Invention] An object of the present invention is to make at least a part of the solvent of the developer solution odorless;
In addition to using a solvent that is stable against high-temperature heating, we have developed a new mixing system that allows efficient contact between ozone and solvent mist.
It is an object of the present invention to provide a wet image forming apparatus which eliminates the above-mentioned problems in the prior art by adding a discharge means, generates little odor, and is capable of efficient ozone decomposition.

[Structure and operation of the invention]

The wet image forming apparatus of the present invention basically includes means for forming an electrostatic latent image on an electrophotographic photoreceptor or electrostatic recording medium, and means for developing the latent image with a developer.

In a wet image forming apparatus that combines a means for electrostatically transferring the obtained image onto a transfer paper and a roller for thermally fixing the transferred image, at least a part of the carrier liquid solvent for the developer is composed of silicone oil. In addition, the present invention is characterized in that a means is provided for collecting and mixing ozone and solvent mist generated within the apparatus, and discharging the same to the outside of the apparatus.

Preferably, the apparatus of the present invention is further provided with a filter for recovering silicone oil within the discharge means and means for circulating the recovered silicone oil into the developer.

The apparatus of the present invention will be explained using a wet-type electrophotographic copying machine shown in FIG. 1 using an electrophotographic photosensitive drum.

In FIG. 1, during copying, the photosensitive drum 1 is driven to rotate at a constant speed in the direction of the arrow by a drive device (not shown), is charged in the negative direction by the main charger 14, and then exposed to light from the exposure system (see the arrow). ) projects the original image to form an electrostatic latent image, and at the same time, the eraser 13 removes static electricity from outside the image forming area of the photoreceptor. The latent image on the photoreceptor drum 1 is formed by the first image on which a developer is applied. A wet developing device equipped with a second developing roller 6.8 develops the obtained toner image, and the resulting toner image is transferred from a paper feeding device (not shown) via a paper feeding roller lO as indicated by a broken line arrow. The image is transferred onto the paper 21 by the transfer charger 11. The transfer paper 21 is separated from the photoreceptor drum 1 by a separation roller (not shown) and conveyed by a conveyor belt 20, and a fixing device equipped with a fixing roller consisting of a heating roller 31 with a built-in heater 33 and a pressure roller 32. After being heat-fixed, the image is ejected outside the machine as a copy. After the transfer paper is separated from the photosensitive drum 1, residual toner and developer are removed by a unit having a cleaning blade 16 and a cleaning form roller 18, and residual potential is further removed by a static eliminator (static eliminator 15 or static eliminator charger). and prepare for the next copy.

Although not shown in the copying machine of FIG. 1, the transfer paper 21 separated from the photosensitive drum 1 is passed between a squeeze roller consisting of a plotter roller and a sponge roller, if necessary, into the boat before fixing. The soaked carrier liquid may be squeezed out.

Further explaining the developing device and the fixing device, in the case of this developing device, a reverse squeeze roller 9 is arranged in addition to the first and second developing rollers 6.8 in the developing container. The second developing roller 6.8 is held at a small distance from the surface of the photosensitive drum 1. 1st. The second developing rollers 6 and 8 are driven by the photosensitive drum l as shown by the arrow.
A cleaning member (scraper) 7, which is rotationally driven relative to the developer container and fixed to the developer container, comes into contact with each developer roller 6.8 and constantly cleans the toner on the developer roller.

The developer supplied from the developer supply nozzle 5 by the developer supply means is uniformly conveyed to the surface of the photoreceptor drum 1 by the rotation of the developer roller 6.8 and the scraper 7, and is further transferred to the surface of the photoreceptor drum 1 and the developer roller 6. After developing the latent image on the photoreceptor drum 1, the developer is discharged from the developer outlet 12.
collected and reused.

The reverse squeeze roller 9 is rotated by a drive device relative to the photoreceptor drum 1 as shown by the arrow to scrape off excess developer on the photoreceptor drum 1, and the developer adhering to the squeeze roller is removed by the scraper 7. scraped off. In the present invention, silicone oil is contained in at least a part of the carrier liquid solvent of the developer.

On the other hand, the fixing device is of a type in which the heating roller 31 directly contacts the toner image surface, and the heating roller 31 and the pressure roller 32 are pressed against each other across the paper passage path of the transfer paper 21 carrying unfixed toner. It is arranged like this. A pressure lever 34 is pressed against the shaft portion of the pressure roller 32 by a biasing force of a spring 35, and thereby the pressure roller 3
A predetermined pressure is applied to the roller 2, and a nip is thus formed between the pressure roller and the heating roller. heating roller 31
As mentioned above, the heater 33 is built in as a heat source during fixing. Also, the heater 33 has a heating roller 31.
A thermistor 36 and a temperature fuse 37 are attached to the outside to control the temperature. Further, a separation claw 38 and a release agent coating felt 39 are arranged on the outer peripheral surface of the heating roller 31 so as to be in contact with each other. Note that 43 is a release agent tank connected to the felt 39.

In addition, 2 is a pump for pumping up the developer, 3 is a toner concentration sensor, 4 is a pipe that supplies the developer drawn up from the developer tank 22 by the pump 2 to the developing roller 6.8, and 5
is a developer supply nozzle provided at the tip of this supply pipe, 1
9 is a pipe for discharging the developer discharged from the developer outlet 12 to the original tank 22 for reuse, 23 is a liquid level detection float sensor, 24 is the exterior body of the developing unit, and the developer receiver is a plate. It also serves as Further, 17 is a Urahami scattering plate, and 19 is a drain hole.

In the present invention, the main charger 14. The ozone generated from the transfer charger 11, etc. is brought into efficient contact with the developer on the developing roller 6.8, the developer attached to the photoreceptor drum 1 and the transfer paper 21, and the solvent mist generated from the cleaning unit, fixing unit, etc. After efficiently decomposing ozone, a means for collecting, mixing, and discharging ozone and solvent mist is used to discharge the ozone and solvent mist. In FIG. 1, this means consists of a duct 41 having a suction fan 40 at its outlet. Note that 42 is a filter for recovering silicone oil. Ozone and solvent mist generated in the apparatus are collected by a suction fan 40 in a duct 41 as shown by the arrow (in the case of a fixing unit, it is preferable to collect them from the center of the duct 41 as shown in the figure), and mixed. As a result, the same components come into contact with each other efficiently, and after the ozone is efficiently decomposed, it is discharged. At this time, the solvent mist contains heat-stable silicone oil, so there is little odor. Of course, if all the solvent in the developer is silicone oil, there will be no odor at all. In addition, since a filter 42 is disposed in the duct 41 near the discharge port, the silicone oil mist in the solvent mist is trapped by the filter 42, cooled and turned into droplets, which pass through the lower liquid pool to the developing tank 22. will be collected within. Note that the filter 42 can further increase the contact efficiency with ozone by trapping silicone oil. In any case, if the suction fan is too strong, it will remove heat during fixing, so in order to save energy, it is desirable to set the suction power in a balanced manner, and use a filter with low pressure loss.

The silicone oil used as at least a part of the carrier liquid solvent of the developer in the present invention may be any silicone oil as long as it is liquid and has a siloxane structure, such as dimethyl silicone, methylphenyl silicone, cyclic silicone (
cyclic polysiloxanes) and mixtures thereof.

As the solvent other than silicone oil, paraffinic or isoparaffinic aliphatic hydrocarbons such as nonane, decane, isododecane, isooctane, ligroin, etc. are used as in the past. However, silicone oil alone is preferable in that it does not generate any strange odor or odor.

〔Example〕

The present invention will be explained below by way of examples.

Examples 1 to 7 A developing solution using the solvent shown in the table below as a carrier liquid was put into the developing tank 22 of the wet-type electrophotographic copying machine shown in FIG. 1, and Ricoh Type 6200 was set as transfer paper (A4 size). , linear speed 266 mm/sec, fixing temperature 140
Continuous copying was carried out for 8 hours (19,200 sheets) under conditions of ±10°C, and ozone concentration and odor were measured. A similar test was also conducted without paper passing. The measurement environment was 23±2℃-55±5%RH.

The measurement chamber had a volume of 30 m and no ventilation, and the measurement nozzle was located 20 cm away from the outlet of the duct 41.

*1: CLD ozone analysis system DY8410 manufactured by Dyrec
Measured in.

*2: Odorless is 0. 0,1, with extremely strong odor being 5
Measured using a 6-level evaluation method of 2, 3, and 4.5.

*3: Even without solvent, the ozone concentration is 0.13 just by passing the paper through.
The reason for the reduction from 6 ppm to 0.114 ppm is that ozone was decomposed by the moisture evaporated from the transfer paper.

4゜[Operations and Effects of the Invention] The device of the present invention uses silicone oil, which is odorless and stable even when heated at high temperatures, as at least a part of the carrier liquid solvent of the developer, and efficiently converts ozone and solvent mist. Since a means for collecting, mixing and discharging ozone is provided, it is possible to decompose ozone more efficiently than before, and to reduce the generation of off-odor. In this way, ozone decomposition is carried out using solvent mist,
No special filters, decomposers, or their replacements are required.

In addition, if a filter is installed in this collection, mixing, and discharge means, silicone oil can be trapped, collected, and circulated, which is economical.This trap also has the effect of further improving ozone contact efficiency. There is also.

[Brief explanation of drawings]

FIG. 1 is an overall view of a wet type electrophotographic copying machine which is an example of the apparatus of the present invention. 1... Photosensitive drum 6... First developing roller 7... Scraper 8... Second developing roller 9... Reverse squeeze roller 11... Transfer charger 14... Main charger 16...・Cleaning blade 18...Cleaning foam roller 20...Transport belt 31...Heating roller 33...Heater 41...Duct (mixing/collecting/discharging means) 10...
Paper feed port 13... I-S 15... Static elimination lamp 21... Transfer 32... Pressure roller 40... Suction fan 42... Filter paper

Claims (1)

[Scope of Claims] 1. Means for forming an electrostatic latent image on an electrophotographic photoreceptor or electrostatic recording medium, means for developing the latent image with a developer, and electrostatic transfer of the obtained image onto transfer paper. In a wet-type image forming apparatus that combines means for automatically transferring the transferred image and a roller for thermally fixing the transferred image, at least a part of the carrier liquid solvent for the developer is composed of silicone oil, and ozone and A wet type direct image forming apparatus characterized in that a means for collecting and mixing solvent mist and discharging the same to the outside of the apparatus is provided. 2. The apparatus according to claim 1, further comprising a filter for recovering silicone oil within said collecting, mixing and discharging means. 3. The apparatus of claim 2 further comprising means for circulating the recovered silicone oil to the developer solution.